The present invention relates to a fine-line patterning method for use in the manufacture of a semiconductor IC device and the like and a patterning material used in the patterning method.
In manufacturing a semiconductor device including semiconductor elements such as an IC and an LSI, patterning is conventionally effected through photolithography using UV, where a light source with a shorter wavelength is used as the semiconductor devices are more refined. In the application of a light source with a short wavelength, a surface imaging process using dry development has recently been developed in order to increase the depth of focus and improve practical resolution.
As an example of the surface resolving process, U.S. Pat. No. 5,278,029 discloses a method in which, after selectively forming an oxide film of polysiloxane on the surface of a resist film of a resist material which can produce an acid through exposure, the resist film is dry etched, so as to form a resist pattern.
Now, this method of forming the resist pattern will be described with reference to FIGS. 6(a), 6(b), 7(a) and 7(b).
In the following description, a copolymer of 1,2,3,4-tetrahydronaphthyridinenimino-p-styrene sulfonate (NISS) and methyl methacrylate (MMA) is used as the resist material which can produce an acid through exposure.
First, as is shown in FIG. 6(a), a resist film 51 of the resist material, which can produce an acid through exposure, formed on a semiconductor substrate 50 is irradiated with a KrF excimer laser 53 by using a mask 52, thereby producing an acid in exposed areas 51a of the resist film 51. This acid provides the exposed areas 51a with hydrophilicity, and hence, the exposed areas 51a can easily adsorb a water content of air. Accordingly, a natural adsorbing layer 54 with a small thickness, where water is adsorbed, is formed on the surface of each exposed area 51a as shown in FIG. 6(b).
Next, when an alkoxysilane gas is introduced onto the surface of the resist film 51, the acid included in the natural adsorbing layer 54 formed on the exposed area 51a works as a catalyst, so that alkoxysilane is hydrolyzed and dehydrated. As a result, an oxide film 55 is formed on the surface of each exposed area 51a as is shown in FIG. 7(a). Then, by using the oxide film 55 as a mask, the resist film 51 is dry etched by RIE using O.sub.2 plasma 56. Thus, a fine-line resist pattern 57 is formed as is shown in FIG. 7(b).
However, when the resist pattern is formed in the aforementioned manner, the oxide film 55 flows during its growth as is shown in FIG. 8. This disadvantageously enlarges the edge roughness of the oxide film 55.
In particular when the pattern pitch is more refined, edge roughness such as a bridge striding patterns can occur, resulting in degrading the dimensional accuracy of the resist pattern 57.